Grate mechanism



C. DJUVIK GRATE MECHANISM Aug. 2, 1955 l a e h s s t e e h s 2 0m M A 5 9 1 6 2 m r 3 J J m 5 w an d H mm QM @m NV 0M NV 0m INVENTOR. CARL DJ UVI K BY deb-4m; ATTORNEY c. DJ UVlK GRATE MECHANISM Aug. 2, 1955 2 Sheets-Sheet Filed March 26, 1954 FIG.4

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2s 2s VVVVVV 2a 2a 27 27 INVENTOR. CARL DJUVI K ATTORNEY nited States Patent thee 2,714,457 Patented Aug. 2, 1955 i. 2,714,457 GRATE MECHANISM (Iari Djuvik, Star Lake, N. Y., assignor to Jones &

Laughiin Steel Corporation, Pittsburgh, Pa., :1 corporation of Pennsyivania Application March 26, 1954, Serial No. 419,tl43 8 Claims. (Cl. 21418) This invention relates to a grate mechanism adapted for use with a shaft furnace and is more particularly concerned with mechanism for progressively rotating successive bars of a grate and progressively returning such bars to their original positions.

So-called low-grade iron ores must be ground to small particle sizes in order that the desired iron mineral may be separated from accompanying gangue. The beneficiated product resulting from such treatment of ores is not physically suitable for smelting in a blast furnace in the conventional manner. Finely divided ores, when made a part of a blast furnace burden, tend to pack so tightly that the air blast is unable to penetrate the burden, and when this occurs, reduction of the ores cannot take place. For this reason, finely divided iron ore concentrates are agglomerated into larger physical forms which can be reduced by conventional blast furnace smelting. Finely divided iron ores may be formed into more or less spherical balls or pellets by known processes. The pellets as formed do not possess mechanical strength sufficient to permit their use as a constituent of a blast furnace charge. However, these pellets may be hardened and mechanically strengthened by heat treatment. This heat treating may be conventionally carried out in a vertical shaft furnace. The pellets are charged into the top of such a shaft furnace, and hot gaseous combustion products are also introduced into the shaft furnace, generally at a level somewhat below that at which the pellets are charged. The heattreated charge is withdrawn from the bottom of the furnace at intervals, so that the charge in the furnace descends as it is being heated. The charge of pellets at the bottom of the furnace supported by the furnace grates is generally at least partially fused, so that it must be broken up to some extent as it is discharged. The layer of charge resting on the furnace grates can be broken up by rotating these grates, and it is with apparatus for this purpose that my invention is particularly concerned.

It is an object of my invention to provide apparatus capable of causing rotation of a series of furnace grates, one after another, and of returning such grates to their original positions, also one after another, in a specified sequence. It is another object of my invention to provide apparatus capable of accomplishing such grate movement automatically. Further objects will appear in the course of the following description and explanation of my invention.

A present preferred embodiment of my invention is illustrated in the accompanying figures to which reference is now made.

Figure 1 represents a schematic view of the apparatus of my invention, including furnace grates set at one of two operating positions.

Figure 2 is a schematic view of a portion of the apparatus of Figure 1 in which the grate bars are rotated to the second operating position.

Figure 3 represents a cross sectional elevation through a shaft furnace to which my invention may be applied.

Figure 4 is a horizontal cross section through the shaft furnace of Figure 3 taken on the plane IV-IV.

The shaft furnace to which my invention is adapted is provided with an elongated upright chamber 1 having refractory-lined side walls 3--3. The furnace chamber 1 is open at its top 5. Near the top of chamber 1 is positioned a manifold 4 which may surround the chamber 1. This manifold 4 is provided with tuyeres or openings 22 which communicate with the interior of chamber 1. A combustion chamber 6 adjoins manifold 4 at one side thereof and communicates through pipe 7 with a blower 8. Centrally located in pipe 7 just below the plane in which pipe 7 enters the bottom of chamber 6 is a pipe 10 terminated at its upper end in a nozzle or burner tip 11. Pipe 10 is connected to a source of combustible gas, not shown. Surrounding the furnace chamber 1 in a plane below that of manifold 4 is a manifold 13 provided with a plurality of offtakes 1414 communicating with the interior of furnace chamber 1. Manifold 13 opens into pipe 16 which is connected to the intake side of blower 8. Blower 8, which is conveniently a rotary blower, is provided with a motor, not shown, to enable it to draw gases through pipe 16 and below them through pipe 7 into chamber 6. Near the bottom of furnace chamber 1 is positioned a manifold 18 which communicates with the interior of furnace chamber 1 through a plurality of apertures 19-19. Manifold 18 is connected through pipe 21 to the outlet of a blower 22. The intake of blower 22 is open to the atmosphere through entry pipe 23. Blower 22 may also i be a rotary blower and is also provided with a driving motor, not shown. At the bottom of furnace chamber 1 the side walls 25-25 slope downwardly and outwardly. The bottom of furnace chamber 1 is formed by a plurality of parallel grate bars 27-27. Each grate bar 27 is elongated so as to extend across the bottom of the furnace chamber 1 and is rotatable about its long axis on horizontal shaft 28. Each grate bar 27 is an equilateral triangle in vertical cross section. Below the grate bars 2727 is positioned a belt conveyor 30 which extends outwardly beyond shaft furnace chamber 1 and upwardly to remove and elevate the material discharged.

Afiixed to each grate bar shaft 28 is a projecting arm 31. Attached to arm 31 is piston rod 32 of an air cylinder 33. All air cylinders 33 are alike with the exception of one air cylinder which I have designated 33-a, and which may be attached to operate the first grate bar 27 at one side or the other of shaft furnace 1. It is not necessary to my invention that air cylinder 33a operate the first grate bar on either side, but my invention will be described as aranged in this way. I have designated one air cylinder 33-]; for a reason which will appear, but this cylinder 33-h does not differ in any respect from any other cylinder 33. Each cylinder 33, as well as cylinder 33a, is provided with a piston 35. The upper end of each cylinder 33 and cylinder 33-01 is pivotally attached to a fixed structure not shown through pin 36.

Each cylinder 33 is provided at its upper end with a pipe 38 communicating with its interior and at its lower end with a pipe 39, also communciating with its interior. Pipes 38 and 39 are arranged in a conventional manner so that when fluid under pressure is admitted through pipe 38 it forces piston 35 down, and when fluid under pressure is admitted through pipe 39, it forces piston 35 up. Cylinder 33-61 is provided at its upper end with a pipe 33-a and at its lower end with a pipe 39-12. Each cylinder 33, but not cylinder 33a, is provided with a valve 41 which is connected to pipes 38 and 39. Each valve 41 is also connected to a pipe 42, and each pipe 42 is connected to a fluid supply pipe 43. The fluid in pipe 43 may be compressed air. Each valve 41 also connects to an exhaust pipe 45 which may open into the atmosphere. Each valve 41 may be mechanically operated by lever arm 46 and may assume either of two positions. In the first position of valve 41, which is shown in Figure 1, pipe 39 is connected to pipe 42 and pipe 38 is connected to pipe 45. in the second position, shown in Figure 2, pipe 42 is connected to pipe 38 and pipe 45 is connected to pipe 39. Each valve lever arm 46 is pivotally connected to a link 47 which at its other end is pivotally connected to grate bar arm 31 of the next adjoining grate bar 27. Pipe 38 of air cylinder 33b is connected by pipe 49 with pipe 39-11 of air cylinder 33-a. In Figures 1 and 2 air cylinder 33-b is shown as separated by one air cylinder 33 from air cylinder 33-a, but it will be understood that any air cylinder 33 can be cylinder 33-b connected by pipe 49 to air cylinder 33a. As will appear later, the particular air cylinder 33 to be chosen as cylinder 33-b depends upon the pattern of operation of the grates desired.

Pipe 38-a of cylinder 33-a is connected to a check valve 50. This valve is so constructed that fluid passing through it into cylinder 33a is unimpeded, but fluid passing from cylinder 33-a outwardly through valve 50 is retarded. Check valve 50 is also connected with relay valve 51. This valve may be moved into one or the other of two positions. In its first position, as is shown in Figure 1, check valve 50 communicates with pipe 53. In its second position, which is shown by the dotted lines in Figure 2, check valve 50 communicates with pipe 54 which exhausts into the atmosphere. Relay valve 51 is moved from its first to its second position as above described by fluid pressure in pipe 52 which connects relay valve 51 with pipes 39a and 49 previously mentioned. When fluid under pressure is admitted to pipe 52, valve 51 is moved to its second position, but when no fluid under pressure enters pipe 52, valve 51 returns to its first position. Pipe 53 communicates with a manually operable valve 55. This valve also may assume one of two positions. In its second position, as shown in Figure 2, it connects pipe 53 with pipe 56. In its first position, as shown in Figure l, the connection between pipe 53 and 56 is broken, and pipe 53 is connected to pipe 57 which exhausts into the atmosphere. Pipes 43 and 56 are both connected to reducing valve 58 and through it to master valve 59, which in turn is connected to a source of fluid under pressure, such as compressed air, not shown.

Air cylinder 33-a is provided with a spiral spring 34 which is strong enough to overbalance slightly the weight of piston 35, piston rod 32, and associated elements, so that in the absence of any fluid under pressure in cylinder 33-11, spring 34 holds piston 35 in its upward position as is illustrated in Figure 1.

The operation of my apparatus will now be described with reference to the present preferred embodiment described in the preceding paragraphs. Pellets are charged into the open top 5 of shaft furnace chamber 1. A gaseous fuel is admitted to pipe and introduced through nozzle 11 into combustion chamber 6 where it is burned with air blown through pipe 7 by blower 8. The products of combustion in chamber 6 enter the manifold 4 and issue through tuyeres 2-2 into furnace chamber 1, where they are drawn downwardly through the charged pellets and out through oiftakes 14-14, manifold 13, and pipe 16 by blower 8, which again introduces them into chamber 6. Atmospheric air is blown by blower 22 through pipe 21, manifold 18, and openings 1919 into the bottom of furnace chamber 1, where it rises through the hot pellets and is drawn off through offtakes 14-14. This air is preheated by the hot pellets through which it passes and, in turn, cools them somewhat. As has been mentioned, the heat-treated pellets resting on the grates 2727 are at least partially fused and must be broken up if they are to be discharged through the bottom of my furnace. This breaking up and discharge is accomplished by tilting or rocking grate bars 27-27 by the app aratus of my invention.

Let it be assumed that this apparatus is initially in the position as shown in Figure 1. If manually operable valve 55 is moved to the position shown in Figure 2 in which pipe 56 carrying fluid under pressure is connected to pipe 4 53, pressure fluid passes through relay valve 51 and check valve 50, through pipe 38a into the upper end of cylinder 33a. It will be seen from Figure 1 that pipe 39a of cylinder 33-(1 through pipe 49 and valve 41 exhausts into the atmosphere through pipe 45. Therefore, the pressure of the fiuid admitted into the top of cylinder 33-a will force piston 35 down, rotating arm 31 about the axis of shaft 28 and rotating grate bar 27 also about the axis of shaft 28. My apparatus is adjusted so that at the end of the stroke of piston 35 grate bar 27 has been turned through an arc of 120. As arm 31 rotates downwardly, it carries link 47 with it, and link 47 pulls down arm 46 of valve 41, which controls air cylinder 33, which in turn operates the next adjoining grate bar 27. As arm 46 of valve 41 is pulled down to its lower position, as shown in Figure 2, valve 41 turns from its position shown in Figure l to its position shown in Figure 2. In this latter or second position, fluid under pressure from fluid pipe 43 is allowed to flow into pipe 38 communicating with the upper end of air cylinder 33, and pipe 39 leading from the lower end of air cylinder 33 is connected to pipe which exhausts into the atmosphere. The piston rod 42 of cylinder 33 therefore moves down, rotating grate bar 27 to which it is connected. In the same way the movement of each arm 31 associated with a grate bar 27 moves the control valve 41 which is mechanically connected to it from the first position of this valve to the second position, and so the whole series of grate bars is rotated, one bar at a time, from the first grate bar position to the second grate bar position.

When valve 41, associated with cylinder 33-b to which pipe 49 is connected, is moved to its second position, fluid under pressure from pipe 42 is admitted into pipe 49 as well as pipe 38. This fluid moves through pipe 49 into pipe 39-a and also into pipe 52. As has been mentioned, the presence of fluid under pressure in pipe 52 causes relay valve 51 to assume its second position in which check valve is connected to the atamosphere through pipe 54. Therefore, the fluid under pressure from pipe 39-a causes piston 35 in cylinder 33a to rise, which rotates grate bar 27 associated therewith from its second position, as illustrated in Figure 2, back to its first position, as illustrated in Figure 1. Check valve 50 is provided in pipe 38a in order that this reverse movement of piston 35 may be retarded somewhat. The reverse movement of arm 31 associated with cylinder 33-a reverses the position of valve 41 with which it is connected through link 47 and valve arm 46 so that valve 41 again assumes its first position, as illustrated in Figure 1. In this position of valve 41 fluid under pressure from pipe 43 passes through pipe 42 and into pipe 39 which leads into the lower end of cylinder 33. Likewise, pipe 38 leading from the upper end of cylinder 33 is connected to the atmosphere through pipe 45. Therefore, fluid under pressure causes the piston in cylinder 33 to move upwardly, and piston rod 32 moves its associated grate bar 27 from its second position back to its first position. The remaining grate bars 27 are in the same manner moved back one at a time into their first position.

It will be seen that when the fluid pressure in pipe 52 drops off, relay valve 51 returns to its first position as shown in Figure 1, thereby permitting fluid under pressure from fluid supply pipe 56 again to flow into the upper end of cylinder 33a, starting the cycle all over again. Thus, the grate bars of my apparatus will continue rotating successively from a first to a second position and from a second position back to the first position until they are stopped by turning valve 54 into the off position. This above-described movement of my grate bars 27 breaks up the partially fused layer of pellets immediately above the grates and allows the material to fall between grates 27 and also between the end grates 27 and downwardly and outwardly sloping walls 25 at the bottom of my shaft furnace. The broken material falls on conveyor which carries it away from furnace 1 and upwardly to a discharge station, not shown.

As has been mentioned, any cylinder 33, except, of course, cylinder 33a, may be made cylinder 33-b, which is back connected to cylinder 33-a. In the embodiment of my invention illustrated in Figures 1 and 2, cylinder 33-a is the first cylinder on the right and cylinder 33-h is the third cylinder from the right. With this arrangement of apparatus after the third grate bar 27 from the right has been rotated from its first to its second position, the first grate bar 27 on the right is rotated back from its second to its first position, commencing the return cycle of all grate bars 27. If cylinder 33-17 were the fourth cylinder from the right, for example, the return cycle of grate bar rotation would commence after the fourth grate bar from the right had been rotated from its first to its second position.

When all grate bars 27 are in the position shown in Figure l, the rotation of the first grate bar 27 at the right side of the grate to its position shown in Figure 2 shifts that portion of the charge resting directly on the grate bar toward the right, and allows it to drop through the opening between this grate bar and downwardly and outwardly extending wall portion 25. This opening, when grate bar 27 is in the position shown in Figure 2, is better adapted to discharge pellets than when grate bar 27 is in the position of Figure l, as may be seen. Like rotation of the next adjoining grate bar shifts that portion of the charge resting directly on it into the space vacated by the portion of the charge dumped by rotation of first grate bar 27, and so on across the grate. However, after the second grate bar 27 from the right has been rotated to its position in Figure 2, rotation of successive grate bars across the grate does nothing to assist discharge of the material above first grate bar 27. It is for this reason that I back-connect a selected air cylinder 33-17 to my first air cylinder 33-a in the manner described. This arrangement causes first grate bar 27 to rotate back into its position of Figure 1 after a predetermined interval, again agitating that portion of the furnace charge directly above it and so assisting its discharge. Thus, the rate at which the furnace discharges can be adjusted as desired by selection of the proper air cylinder 33 to be made 33-h.

I claim:

1. Apparatus for discharging a shaft furnace comprising in combination a plurality of parallel grate bars each rotatable about its long axis, a source of fluid under pressure, individual fluid operated means for rotating each grate bar between a first grate position and a second grate position provided with a first conduit admitting fluid urging said fluid operated means toward said first grate position and a second conduit admitting fluid urging said fluid operated means toward said second grate position, a manually operated valve means for connecting said source of fluid with said second conduit of a first said fluid operated means, valve means associated with each other said fluid operated means movable from a first valve position in which said first conduit is connected with said source of fluid and said second conduit is connected with an exhaust to a second valve position in which said first conduit is connected with an exhaust and said second conduit is connected with said source of fluid, means linking each grate bar with the valve means associated with the next adjoining grate bar, whereby said valve means is moved to said first valve position when said grate bar is moved to said first grate position and to said second valve position when said grate bar is moved to said second grate position, an interlock conduit connecting said second conduit of a fluid operated means other than said first fluid operated means to said first conduit of said first fluid operated means, and means operable by the pressure of the fluid in said interlock conduit for connecting said second conduit of said first fluid operated means with an exhaust.

2. The apparatus of claim 1 in which each grate bar is triangular in cross section and the angle between the first grate position and the second grate position is 3. The apparatus of claim 1 in which the manually operated valve means in its off position connects the second fluid conduit of a first said fluid operated means with an exhaust, and said first fluid operated means is provided with mechanical means urging it toward the first grate position.

4. The apparatus of claim 1 in which a check valve is positioned in said second conduit of said first fluid operated means restricting the flow of fluid into said first fluid operated means only.

5. Apparatus for discharging a shaft furnace comprising in combination a plurality of parallel grate bars each rotatable about its long axis, individual operating means for each grate bar moving in a forward direction for rotating a bar from a first grate position to a second grate position and moving in a reverse direction for rotating a bar from said second grate position to said first grate position, manually operable control means causing a first one of said operating means to move in said forward direction, individual control means associated with each other said operating means, each said control means being actuated by movement of the next adjoining grate bar from said first grate position to said second grate position to cause sequential movement of its associated operating means in said forward direction and by movement of said next adjoining grate bar from said second grate position to said first grate position to cause sequential movement of its associated operating means in said reverse direction, and means interconnecting one of said operating means other than said first operating means with said first operating means to cause said first operating means to move in said reverse direction when said operating means other than said first operating means moves in said forward direction.

6. Apparatus for discharging a shaft furnace comprising in combination a plurality of parallel grate bars disposed side by side, each rotatable about its long axis, individual operating means for each grate bar moving in a forward direction for rotating a bar from a first grate position to a second grate position and moving in a reverse direction for rotating a bar from said second grate position to said first grate position, manually operable control means causing a first one of said operating means to move in said forward direction, and means interconnecting each following said operating means with the said grate bar next preceding it adapted to bring about sequential movement of each said operating means in a forward direction following forward movement of the said operating means next preceding it and sequential movement of each said operating means in a reverse direction following reverse movement of the said operating means next preceding it.

7. The apparatus of claim 6 including means interconnecting a said operating means other than the first said operating means with said first operating means adapted to bring about sequential movement of said first operating means in a reverse direction following forward movement of said other operating means.

8. Apparatus for discharging a shaft furnace comprising in combination a plurality of parallel grate bars disposed side by side, each rotatable about its long axis, individual means adapted to rotate each said grate bar between a first grate position and a second grate position, means interconnecting said individual means for each following said grate bar with the said grate bar next preceding it adapted to bring about sequential rotation of each said following grate bar following rotation of said next preceding grate bar.

References Cited in the file of this: patent UNITED STATES PATENTS 2,688,393 Uschmann Sept. 7, 1954 

